1. Field of the Invention
The present disclosure relates to an apparatus, system, and method of inspecting an image formed by an image forming apparatus, and a non-transitory computer-readable medium storing an image inspection control program.
2. Description of the Related Art
Conventionally, inspection of printed matter has been performed by human operators. In recent years, inspection apparatuses that automatically inspect printed matter have been widely used, mainly in the field of offset printing. For example, in conventional devices, a master image would be generated by reading specific printed matter that was selected based on image quality, as a reference image. Corresponding portions of the master image and a subsequently read image of printed matter would be compared to determine, by the degree of difference therebetween, whether there was a defect in the printed matter.
Printing apparatuses, such as electrophotographic apparatuses, have been widely used to print a small number of pages. For example, a printing apparatus may perform variable printing in which the printed contents differ on each page. In such a case, comparing the printed matter, with a master image generated from previously printed matter, would be inefficient. In view of this, the master image has typically been generated based on print data and then compared with the printed image to be inspected.
Japanese Patent Application Publication No. 2011-156861-A proposes a method of generating the master image, in consideration of a dot gain, to further the accuracy in determining the defects in the read image.
Specifically, correction of the master image is made according to a dot gain (i.e., pixel output characteristics) for different kinds of sheets, which are determined beforehand. Although JP 2011-156861-A discusses a method of calculating in advance the dot gain (i.e., the output characteristics for each pixel) for each of the kinds of sheets, it does not disclose the method of the calculating in detail. A method of calculating output characteristics for every pixel exactly is required to perform accurate correction. Furthermore, the output characteristics of every pixel may fluctuate by not only the kind of the sheet but also the state of the device. Therefore, in order to reduce the burden on an operator, a method of calculating dot gain that is effective and capable of being repeated effectively is needed. In addition, such a problem can equally occur for other recording media such as films, not only to the case of outputting an image to paper.
In view of the above, the inventors of the present embodiments have discovered that there is a need for an apparatus, a system, a method, and a non-transitory computer-readable medium storing an image inspection control program, each of which is capable of calculating an output characteristic for every pixel for correction of an inspection reference image, in the system which inspect a result of an image forming output by comparing between an image read from a recording media and the inspection reference image.